Formula for comparative evaluation of the efficience of a flat solar air heater with a wavy absorber

In the article, for the hot climate of the Republic of Uzbekistan, the use of flat solar air heaters for drying agricultural products is recommended. Considering the low efficiency of heat transfer from the absorber to the air, such heaters use intensification of heat transfer, which can be organized by using a wavy surface on which the turbulization of the flow near the wavy wall increases. Since turbulators also increase the flow resistance, which leads to an increase in fan power costs, the article proposes a formula for calculating the thermal efficiency of a flat solar air heater, taking into account the equality of power costs for moving air into the flat solar air heater with a profile absorber and in the heater without turbulators. For the selected absorber surface (diffuser-confuser type), the calculation of the thermal efficiency of the flat solar air heater is shown.